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Bariatric surgery alters the physiology of the stomach to treat obesity by reducing overeating, leading to improvements in diabetes control, cardiovascular health, and quality of life.

The three most common procedures are Sleeve Gastrectomy, Adjustable Gastric Banding, and Roux-en-Y/ Omega Loop Gastric Bypass. Close follow-up and a multidisciplinary approach involving dietitians, exercise physiologists, and psychologists are essential to successful outcomes.

“Weight-loss (Bariatric) surgery is currently the only intervention that can provide significant and long-term weight loss for the morbidly obese.” [1] 

—World Health Organisation

Expected Benefits

Dependant of the person and the procedure, individuals can expect:

  • 17-35% weight reduction in the first 2 years [2]
  • persistent 18% weight reduction up to 20 years [3]
  • reduced cardiovascular mortality by 50% up to 14 years [4]
  • in obese diabetics, 50% achieve target HbA1c≤7.0% at 5 years [5]
  • in obese diabetics, 12-25% cessation of hypoglycaemic medications at 5 years [5]
  • in sleep apnoea, reduced average respiratory distress index from severe to mild [6]
  • improved quality of life scores by 16-17 on the RAND SF-36 survey [5]

First Steps

The NHMRC recommends bariatric surgery[7] be considered for

  • individuals with BMI >40 kg/m2
  • individuals with BMI >35 kg/m2 with one or more obesity-related complications.

In a consensus statement by major international diabetes organisations endorsed by the Australian Diabetes Society[8], bariatric–metabolic surgery is recommended for

  • all individuals with T2 diabetes and BMI ≥40 kg/m2
  • individuals with BMI 35–40 kg/m2 with inadequate glycaemic control despite lifestyle and optimal medical therapy.

In consultation, patients will be offered the most appropriate options depending on their BMI, co-morbidities, age, and other factors. As a guide:

Adjustable gastric banding is the least invasive bariatric procedure with the fewest perioperative complications. However, some patients will require band removal due to insufficient weight loss, GORD symptoms, or band slippage. It  requires ongoing medical management to adjust the band, although once stable the band may not need adjustment for months or years. Banding is well suited to older patients, those with higher operative risk, and those at the lower BMI range of obesity.

Sleeve gastrectomy is moderately invasive as it involves the removal of around 70-80% of the stomach. Unlike banding, this procedure is not reversible. It can also cause increased GORD symptoms, however insufficient weight loss is less common and there is no band so there can be no slippage. Patients need fewer ongoing medical visits compared to banding, however they still require regular review for nutritional status. Sleeve gastrectomy is well suited to patients who require moderate weight loss or who have not had success with banding.

Roux-en-Y and Omega Loop gastric bypass is the most invasive bariatric procedure with the greatest postoperative morbidity, however it has the greatest average weight loss, and unlike banding and sleeve gastrectomy, it may reduce GORD symptoms. If necessary the bypass can be surgically reversed, although this is uncommon. As for gastrectomy, ongoing nutrition review is essential. Bypass is well suited for patients with higher BMIs, those with significant GORD, or where other procedures have not been successful.

SUMMARY OF BARIATRIC SURGERY OPTIONS
        Adjustable gastric band Sleeve gastrectomy Roux-en-Y gastric bypass
DESCRIPTION

Adjustable silicone band placed just below the gastroesophageal junction, applying gentle pressure that suppresses hunger. Level of restriction can be adjusted by varying the amount of fluid placed in the band

Greater portion of the fundus and body of the stomach is removed. Gastric volume is reduced by about 80%

1. Small stomach pouch created, thereby reducing gastric volume.

2. The pouch is joined to the jejunum, hence, diverting nutrients from lower stomach, duodenum and proximal jejunum

MEAN TOTAL BODY WEIGHT LOSS
17-20%
20-30%
25-35%
MORTALITY RATE AT 30 DAYS
0.03–0.1%
0.3–0.5%
0.1–0.4%
MORBIDITY AT 1 YEAR
4.6%
10.8%
14.9%
NUTRITIONAL CONCERNS
Low (deficiencies in iron, vitamin B12, folate, thiamine)
Moderate (deficiencies in iron, vitamin B12, folate, calcium, vitamin D, thiamine, copper, zinc)
Moderate (deficiencies in iron, vitamin B12, folate, calcium, vitamin D, thiamine, copper, zinc)
ADVANTAGES
Effective, with good long-term weight maintenance Degree of restriction adjustable Reversible Lowest morbidity and mortality rate
Very effective with good mid-term weight maintenance
Largest amount of weight loss with good long-term weight maintenance Highest rate of diabetes remission (for patients with pre-existing type 2 diabetes mellitus)
DISADVANTAGES & KEY COMPLICATIONS
Highest long-term re-operation rate Gastric pouch dilatation, erosion of band into the stomach, leaks to the adjustable gastric band system, weight regain
Staple line leak, gastroesophageal reflux disease, dilatation of the gastric remnant, weight regain Limited long-term data
Staple line leak, dumping, stomal ulcer, intestinal obstruction, gallstones, nutritional deficiency, altered alcohol metabolism, weight regain

Before the Procedure:

Initial work-up

We tailor assessment according to the individual’s risk factors. Common clinical observations and investigations include:

History:

Weight history (eg age of onset of obesity, minimum and maximum weight), previous weight loss attempts (including diets, medications, previous weight-loss surgery), triggers for weight gain/regain. Obesity-related comorbidities, family history, medication history. Current lifestyle: dietary behaviour and physical activity levels; work and home environment, psychosocial support.

Physical Examination:

Weight, body mass index, blood pressure. Signs of specific causes of obesity (eg hypothyroidism, Cushing’s syndrome).

Investigations:

Full blood count, urea and electrolytes, liver enzymes, coagulation screen, fasting lipids and glucose, HbA1c.

In known T2DM, C-peptide for pancreatic beta cell function.

Nutrition: ferritin, vitamin B12, folate, 25-OH vitamin D and Zinc.

For individuals with specific risks: ECG, echocardiogram or cardiology referral. Endoscopy for GORD, upper GI ultrasound for NASH or gallstones. Polysomnography for sleep apnoea.

Psychological:

Assess commitment, motivation, readiness to change, as well as understanding and expectations of surgery. Psychiatry review if known or suspected history of psychiatric illness or substance abuse.

We welcome referrals that include essential investigations as this can expedite the assessment process, however it is not necessary.

Pre-operative assessment

Once a decision has been made for bariatric–metabolic surgery, a series of detailed assessments would be organised.

Nutritional assessment:

Every patient will see one of the dietitians at the SCMWLC prior to surgery. In this session, they will be prepared for what the journey ahead will look like from a nutritional perspective.  A state of high-energy malnutrition is often observed in clinically severe obesity, which is masked by ample energy excess. Up to 80% of bariatric–metabolic surgery candidates have micronutrient deficiencies pre-operatively, and appropriate nutritional assessment allows deficiencies to be corrected prior to surgery.

Identifying and optimising complications prior to surgery:

Pre-operative assessment also includes identification and optimisation of obesity-related complications, with the aim to improve peri-operative safety and outcomes after surgery.

Psychological assessment:

Prior to surgery, thorough assessment of the patient’s behaviour, home and work environments, family dynamics, and their ability to incorporate nutritional and lifestyle changes should be conducted. Incorrect beliefs and unrealistic expectations on what the procedure can achieve must be rectified. Depression, anxiety and other psychiatric disorders are prevalent in individuals considering bariatric–metabolic surgery.

Anatomical assessment:

As part of the pre-operative assessment, evaluation of the upper gastrointestinal anatomy may be performed, depending on factors such as the presence of gastrointestinal symptoms or type of surgery being considered.

Post-operative Care

Lifestyle changes after surgery

The team at SCMWLC have a very strong presence in the patient’s journey post-surgery.

WEEK OF SURGERY

The team will do a post-operative phone call with the patient to ensure they are travelling well and to answer any questions or concerns they may have coming into the weekend

1 WEEK AFTER

Post operative appointment with Dr Baxter where he will assess the wounds and how the patient is

3 WEEKS AFTER

Appointment with the Dietitian where they will prepare the patient for the soft stage

8 WEEKS AFTER

Appointment with the Dietitian where they will prepare the patient to move to full food

3 MONTHS AFTER

Appointment with both the Dietitian and Dr Baxter to assess their weight loss and how they are travelling

6 MONTHS AFTER

Appointment with Psychologist and Dietitian. This is a very important appointment where the team organise full bloods to be taken prior to. The dietitian will assess their blood levels to make sure they are not lacking anything and that they are getting in enough protein and having a healthy relationship with food. The psychologist will meet up with the patient at 6 months, as this appears to be the time when patients experience “the head games”.

12 MONTHS AFTER AND ANNUALLY

The Bariatric GP will follow up with the patient and organise full bloods to ensure they are not malnourished.

Maintenance of physical activity post bariatric–metabolic surgery aids in maintaining muscle strength, enhanced fitness and greater weight loss. Moderate-intensity physical activity of at least 150 minutes per week and a future target of 300 minutes per week (including strength training) two to three times per week is recommended.

Adjustment of chronic medications

In patients with T2DM, adjustments to the antidiabetes agents are frequently necessary in the early postoperative period to prevent hypoglycaemia. Insulin secretagogues (ie sulphonylureas, metiglinides) should be discontinued and insulin doses reduced as appropriate. Metformin may be continued postoperatively and withdrawal considered if stable non-diabetic glycaemia (ie glycated haemoglobin in the normal range) is demonstrated. Screening for diabetes complications should continue even with diabetes remission, at least for the first five years.

The effect of weight loss on lipids, especially low-density lipoprotein, is variable and generally modest. Therefore, lipid-lowering medications should not be discontinued unless clearly indicated. Although blood pressure often improves with weight loss. Antihypertensives should be actively titrated on follow-up. Medications with a narrow therapeutic index (eg warfarin, digoxin, lithium, antiepileptic medications) also require close monitoring and titration because of altered oral drug bioavailability following bariatric–metabolic surgery.

Post-operative Review Checklist[9]

Monitor weight loss progress and complications at each visit
Monitor adherence to appropriate diet and physical activity levels
Medication review

- Avoid nonsteroidal anti-inflammatory drugs (use them occasionally only)
- Adjust antihypertensives, lipid medications as appropriate
- Adjust diabetes medications- requirement for anti-diabetes medications often decreases, and in many cases, diabetes remission is achieved. Preference for use of agents with favourable weight profile.

Nutritional supplements

- Adult multivitamin and multimineral – containing iron, folic acid, thiamine, vitamin B12. Doses: two daily for sleeve gastrectomy or Roux-en-Y or Omega Loop gastric bypass; one daily for adjustable gastric band
- Citrated calcium – elemental calcium 1200–1500 mg/day
- Vitamin D – titrate to 25-OH vitamin D levels >30 ng/mL. Typical dose required 3000 IU/day
- Additional iron and vitamin B12 supplementation as required, based on lab results

Laboratory assessment

- Every 6-12 months: Full blood count, urea and electrolytes, liver function tests, uric acid, glucose, lipids, Zinc and Vit A
- Every 12 months: 25-OH vitamin D, iPTH, calcium, albumin, phosphate, B12, folate, iron studies, Zinc and Vit A (more frequently if deficiencies identified)

Complications to watch for[9]

Early complications

Surgical complications (eg leaks, perforations, obstruction, infection, haemorrhage)

Abdominal pain, tachycardia, breathlessness, drop in haemoglobin

Usually detected during immediate postoperative period and managed by the surgical team

Presence of these symptoms should prompt urgent referral back to the surgical team

Hypoglycaemia (usually in patients with pre-existing diabetes)

Sweating, dizziness, headaches, palpitations

Low capillary blood glucose on testing

Fairly common, especially in patients on insulin or insulin secretagogues

Stop sulphonylureas, and stop insulin or decrease dose

Close self-monitoring of capillary blood glucose

Dumping syndrome after Roux-en-Y bypass

Abdominal pain, diarrhoea, nausea, flushing, palpitations, sweating, agitation, and syncope after meals rich in simple carbohydrates

Dietary modification, with small regular meals containing protein and complex carbohydrates

Acarbose may be helpful in some refractory cases

Later complications

Iron-deficiency anaemia

Microcytic, hypochromic anaemia, lethargy, anorexia, pallor, hair loss, muscle fatigue

Oral iron supplements, consider intravenous iron for severe deficiency

Vitamin C to increase iron absorption

Rule out bleeding ulcers, neoplastic disease or diverticular disease

B12 deficiency

Macrocytic anaemia, leukopenia, glossitis, thrombocytopenia, peripheral neuropathy

Vitamin B12 repletion (oral or intramuscular)

Prevention – B12 containing multivitamin supplementation

Annual serum B12 level evaluation

Thiamine deficiency

Neurological symptoms, Wernicke’s encephalopathy in severe cases

Appropriate postoperative diet, with regular dietitian follow-up

Screen for other nutritional deficiencies

Thiamine supplementation

Over-restricted gastric band (for patients with adjustable gastric band)

Maladaptive eating, gastro-oesophageal reflux disorder, vomiting, regurgitation, chronic cough, or recurrent aspiration pneumonia

Reduce amount of fluid in gastric band

Consider referral to bariatric surgeon for assessment of band position and function

Weight regain

Maximal weight loss usually achieved at one to two years after surgery, with some weight regain thereafter

For patients with laparoscopic adjustable gastric band – evaluation of band, adjust as required

Consider adjuncts (eg very low energy diet, pharmacotherapy)

*Consider referral back to weight management clinic

Care plans & Financial Access

Bariatric surgery is an investment in future health. Although bariatric surgery is demonstrably cost-effective,[10,11] affordability can be a barrier to individuals in the short term. Here are some ways to improve affordability:

More info on our Pricing page or ask your private health insurer today.  

Care Plan + Team Care Arrangement. Patients with complex chronic health problems such as obesity are eligible under Medicare for 5 subsidised allied health consultations per year. These may include dietitian, exercise physiology, physiotherapy, or psychology visits. We suggest referring for 5 dietitian visits

Mental Health Care Plan. Psychology review is an essential part of the bariatric management cycle, however MHCP eligibility under Medicare is limited to patients with “a mental disorder who would benefit from a structured approach to the management of their treatment needs.”[12] Despite the psychological factors involved, obesity is not considered a mental disorder. A GP might consider an MHCP if the patient has an existing mental health disorder that would benefit from consultation with one of our clinical psychologists at SCMWLC.

More info on our Pricing page or ask your superannuation fund today.  

Further information

www.racgp.org.au/afp/2017/july/bariatric–metabolic-surgery-a-guide-for-the-primary-care-physician/

References

  1. Kaplan, Warren, et al. Priority Medicines for Europe and the World 2013 Update. World Health Organisation, 2013.
  2. Sjöström L, Narbro K, Sjöström CD, et al. Effects of bariatric surgery on mortality in Swedish obese subjects. N Engl J Med 2007;357(8):741–52.
  3. Sjöström L. Review of the key results from the Swedish Obese Subjects (SOS) trial – A prospective controlled intervention study of bariatric surgery. 
J Intern Med 2013;273(3):219–34.
  4. Kwok CS, Pradhan A, Khan MA, et al. Bariatric surgery and its impact on cardiovascular disease and mortality: A systematic review and meta-analysis. Int J Cardiol 2014;173(1):20–28.
  5. Schauer PR, Bhatt DL, Kirwan JP, Wolski K, Aminian A, Brethauer SA, et al. Bariatric surgery versus intensive medical therapy for diabetes — 5-year outcomes. N Engl J Med 2017;376(7):641–51. doi: 10.1056/nejmoa1600869
  6. Haines KL, Nelson LG, Gonzalez R, Torrella T, Martin T, Kandil A, et al. Objective evidence that bariatric surgery improves obesity-related obstructive sleep apnea. Surgery 2007;141(3):354–8. doi: 10.1016/j.surg.2006.08.012
  7. National Health and Medical Research Council. Clinical practice guidelines for the management of overweight and obesity in adults, adolescents and children in Australia. Melbourne: NHMRC, 2013. Available at www.nhmrc.gov.au/about-us/publications/clinical-practice-guidelines-management-overweight-and-obesity [Accessed 18 Aug 2019].
  8. Diabetes Australia. National Position Statement on weight loss surgery (bariatric surgery) and its use in treating obesity or treating and preventing diabetes [online]. 2011. Available at: https://static.diabetesaustralia.com.au/s/fileassets/diabetes-australia/23e8bc73-ca89-46bc-bb79-57dae257d89c.pdf [Accessed 19 Aug 2019].
  9. Lee PC, Dixon J. Bariatric–metabolic surgery: A guide for the primary care physician. Australian Family Physician 2017;46(7):465-471.
  10. Picot J, Jones J, Colquitt JL, Gospodarevskaya E, Loveman E. The clinical effectiveness and cost-effectiveness of bariatric (weight loss) surgery for obesity: a systematic review and economic evaluation. Health Technol Assess 2009;13(41) doi: 10.3310/hta13410
  11. Hoerger TJ. Economics and Policy in Bariatric Surgery. Current Diabetes Reports. 2019;19(6). doi: 10.1007/s11892-019-1148-z
  12. Medicare Benefits Schedule – Note AN.0.56 [online]. Available from: http://www9.health.gov.au/mbs/fullDisplay.cfm?type=note&qt=NoteID&q=AN.0.56 [Accessed 18 Aug 2019].

—CL 2019